Population Genomics and Mate Choice Behaviour of the
Southern Blue-Ringed Octopus (Hapalochlaena maculosa)
A project undertaken at the College of Marine and Environmental Sciences, James Cook University, and supervised by Associate Professor Kyall Zenger
The Southern Blue-Ringed Octopus (Hapalochlaena maculosa) is an Australian endemic species occurring along the southern coastline of the Australian continent. Despite their relatively large species range, H. maculosa are unique among many marine invertebrates in that they lack a planktonic larval phase. Their limited dispersal ability, specific habitat preferences and short life cycle implies that the connectivity of wild H. maculosa populations will most likely be low. Furthermore, the morphology of H. maculosa can differ subtly between relatively close geographic regions, and preliminary molecular analyses have revealed that the genetic differentiation between individuals of east and west coast Australian populations is substantial. In our research we are currently using ~30,000 genome-wide SNP loci to investigate the micro-evolutionary processes shaping H. maculosa populations across its geographic range. By doing this we hope to unravel both fine-scale and broad-scale patterns of connectivity, and uncover evidence of selection impacting this species. This information will enable us to identify whether there might be sex-specific dispersal patterns, signs of local adaptation, any kinds of barriers restricting species connectivity and the existence of any subspecies and/or hybrid zones.
Additionally, we are investigating several aspects of mate choice behaviours in H. maculosa that we are observing within laboratory experiments. Several features of H. maculosa’s life history make it an interesting and unique animal model for studying mechanisms and impacts of sexual selection. Like most cephalopods, H. maculosa has only a very brief life span with a relatively high investment towards reproduction. Hapalochlaena maculosa lives for seven months, and both males and females of this species designate their final one to two months seeking out copulations with multiple partners during a single terminal-breeding season. During this time, males allocate up to approximately fifty finite spermatophores to copulations with different females, and females store the sperm they receive from different males until they lay a single egg-clutch of approximately fifty eggs that the females will guard until hatching. As both males and females of this species have a limited set of gametes and are highly promiscuous, this mating system is ideal for investigating dynamics of both male and female mate choice mechanisms and how they can change with subsequently encountered mates during a breeding season. Our laboratory studies focus on whether males or females are selective of the mates they choose and if so how they choose them. Similarly, we are interested in whether males strategically allocate more or less spermatophores with a female based on her mating history in a manner that would be consistent with predictions of sperm competition. Finally, we also aim to address which males’ that stored sperm end up fertilising a female’s egg clutch, and whether there are consistent patterns in male behaviours or phenotypes that lead to higher paternities.
It is hoped that these studies will increase the current understanding of the taxonomic status and behavioural ecology of one of Australia’s inconspicuous yet charismatic marine macrofauna.
Morse, P., Zenger, K.R., McCormack, M.I., Meekan, M.G. and Huffard, C.l. (2015). Nocturnal mating behaviour and dynamic male invvestment of copulation time in the southern blue-ringed octopus, Hapalochlaena maculosa (Cephalopoda: Octopodidae). Behaviour. DOI:10.1163/1568539X-00003321
Figure Captions (all photos courtesy of Peter Morse)
Figure 1. An alarmed Hapalochlaena maculosa comes out of his shelter to greet a lab observer with an aposematic display.
Figure 2. H. maculosa explores her trial tank prior to experiments
Figure 3. A hungry H maculosa consumes a bait prawn after a long day of experiments
Figure 4. The darker colour morph from and east Albany population
Figure 5. A mother carrying her egg clutch into a pipe for shelter
Figure 6. A mother H. maculosa with her newborn hatchlings
Figure 7. Three H. maculosa respond to odours from different conspecifics during chemosensory trials
Figure 8. Preparing lines of false-shelter traps to obtain new animals near Hillarys, WA
Figure 9. P. Morse uses the research vessel to check trap lines of Rottnest Is.
Figure 10. A new sample is found hiding in a mollusc shell while sifting through bycatch on a commercial fishing vessel